/*
 * Copyright 2002-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.http.server.reactive;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.ByteBuffer;

import javax.net.ssl.SSLSession;

import io.undertow.connector.ByteBufferPool;
import io.undertow.connector.PooledByteBuffer;
import io.undertow.server.HttpServerExchange;
import io.undertow.server.handlers.Cookie;
import org.xnio.channels.StreamSourceChannel;
import reactor.core.publisher.Flux;

import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.http.HttpCookie;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

/**
 * Adapt {@link ServerHttpRequest} to the Undertow {@link HttpServerExchange}.
 *
 * @author Marek Hawrylczak
 * @author Rossen Stoyanchev
 * @since 5.0
 */
class UndertowServerHttpRequest extends AbstractServerHttpRequest {

    private final HttpServerExchange exchange;

    private final RequestBodyPublisher body;


    public UndertowServerHttpRequest(HttpServerExchange exchange, DataBufferFactory bufferFactory)
            throws URISyntaxException {

        super(initUri(exchange), "", new UndertowHeadersAdapter(exchange.getRequestHeaders()));
        this.exchange = exchange;
        this.body = new RequestBodyPublisher(exchange, bufferFactory);
        this.body.registerListeners(exchange);
    }

    private static URI initUri(HttpServerExchange exchange) throws URISyntaxException {
        Assert.notNull(exchange, "HttpServerExchange is required");
        String requestURL = exchange.getRequestURL();
        String query = exchange.getQueryString();
        String requestUriAndQuery = (StringUtils.hasLength(query) ? requestURL + "?" + query : requestURL);
        return new URI(requestUriAndQuery);
    }

    @Override
    public String getMethodValue() {
        return this.exchange.getRequestMethod().toString();
    }

    @SuppressWarnings("deprecation")
    @Override
    protected MultiValueMap<String, HttpCookie> initCookies() {
        MultiValueMap<String, HttpCookie> cookies = new LinkedMultiValueMap<>();
        // getRequestCookies() is deprecated in Undertow 2.2
        for (String name : this.exchange.getRequestCookies().keySet()) {
            Cookie cookie = this.exchange.getRequestCookies().get(name);
            HttpCookie httpCookie = new HttpCookie(name, cookie.getValue());
            cookies.add(name, httpCookie);
        }
        return cookies;
    }

    @Override
    @Nullable
    public InetSocketAddress getLocalAddress() {
        return this.exchange.getDestinationAddress();
    }

    @Override
    @Nullable
    public InetSocketAddress getRemoteAddress() {
        return this.exchange.getSourceAddress();
    }

    @Nullable
    @Override
    protected SslInfo initSslInfo() {
        SSLSession session = this.exchange.getConnection().getSslSession();
        if (session != null) {
            return new DefaultSslInfo(session);
        }
        return null;
    }

    @Override
    public Flux<DataBuffer> getBody() {
        return Flux.from(this.body);
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T getNativeRequest() {
        return (T) this.exchange;
    }

    @Override
    protected String initId() {
        return ObjectUtils.getIdentityHexString(this.exchange.getConnection());
    }


    private class RequestBodyPublisher extends AbstractListenerReadPublisher<DataBuffer> {

        private final StreamSourceChannel channel;

        private final DataBufferFactory bufferFactory;

        private final ByteBufferPool byteBufferPool;

        public RequestBodyPublisher(HttpServerExchange exchange, DataBufferFactory bufferFactory) {
            super(UndertowServerHttpRequest.this.getLogPrefix());
            this.channel = exchange.getRequestChannel();
            this.bufferFactory = bufferFactory;
            this.byteBufferPool = exchange.getConnection().getByteBufferPool();
        }

        private void registerListeners(HttpServerExchange exchange) {
            exchange.addExchangeCompleteListener((ex, next) -> {
                onAllDataRead();
                next.proceed();
            });
            this.channel.getReadSetter().set(c -> onDataAvailable());
            this.channel.getCloseSetter().set(c -> onAllDataRead());
            this.channel.resumeReads();
        }

        @Override
        protected void checkOnDataAvailable() {
            this.channel.resumeReads();
            // We are allowed to try, it will return null if data is not available
            onDataAvailable();
        }

        @Override
        protected void readingPaused() {
            this.channel.suspendReads();
        }

        @Override
        @Nullable
        protected DataBuffer read() throws IOException {
            PooledByteBuffer pooledByteBuffer = this.byteBufferPool.allocate();
            try {
                ByteBuffer byteBuffer = pooledByteBuffer.getBuffer();
                int read = this.channel.read(byteBuffer);

                if (rsReadLogger.isTraceEnabled()) {
                    rsReadLogger.trace(getLogPrefix() + "Read " + read + (read != -1 ? " bytes" : ""));
                }

                if (read > 0) {
                    byteBuffer.flip();
                    DataBuffer dataBuffer = this.bufferFactory.allocateBuffer(read);
                    dataBuffer.write(byteBuffer);
                    return dataBuffer;
                } else if (read == -1) {
                    onAllDataRead();
                }
                return null;
            } finally {
                pooledByteBuffer.close();
            }
        }

        @Override
        protected void discardData() {
            // Nothing to discard since we pass data buffers on immediately..
        }
    }

}
